AB0120 DIFFERENT PATTERNS OF LONGITUDINAL CHANGES IN ANTINUCLEAR ANTIBODIES TITRES IN CHILDREN WITH SYSTEMIC LUPUS ERYTHEMATOSUS
Authors: P. Morán Álvarez, C. Bracaglia, V. Messia, L. Giovannelli, I. Caiello, F. De Benedetti, E. Marasco
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the presence of antinuclear antibodies (ANA). Monitoring of anti-DNA antibody levels may reflect disease activity, by contrast a single anti-RBP antibody determination is thought to suffice for clinical purposes. Recent data suggests that ANA levels may decrease over time secondary to the natural history or to treatments. <h3>Objectives</h3> To investigate the trend of ANA and anti-dsDNA titers over time in children with a diagnosis of SLE. <h3>Methods</h3> We enrolled 15 children with SLE. ANA and anti-dsDNA testing were carried out in all patients from diagnosis every 3-4 months for 2 years. ANA were defined as negative for titers &lt; 1:80. Laboratory parameters, clinical and demographic data was retrieved and analyzed. Interferon Gene Signature (IGS was assessed by the expression of 6 interferon-induced genes (IFI27, IFI44L, IFIT1, ISG15, RSAD2, SIGLEC1) in whole blood RNA. Statistical analysis was performed with SW R_v. 4.0.3. <h3>Results</h3> Following 2 years of follow-up, all patients had ANA titers significantly lower than at time of the onset (MWW, p=0.0002) (Figure 1A). After two years of follow-up, 11 patients (73%) remained ANA positive (group 1), while 4 patients (26%) became negative (group 0). At time of diagnosis no significant differences in ANA titers (MWW, p=0.74) nor in disease activity, measured by SLEDAI, (MWW, p=0.88) were observed (table 1; Figure 1E). No significant differences in organ involvement were observed (Table 1). Assessing the change over time in ANA titers, the 2 groups of patients showed 2 different patterns: in group 0, ANA titers quickly declined and disappeared in the first 6 months after diagnosis; in group 1, ANA titers declined more slowly, remaining positive at 2 years (Figure 1C). ANA pattern (by IFA) was also evaluated, changes from homogenous pattern to speckled was observed during follow up (Figure 1B). Both C3 and C4 increased, with no different patterns between the 2 groups (Figure 1D). Similarly, anti-dsDNA antibodies titers declined over time with no clear different patterns between the groups (Figure 1C). We also analyzed the levels of IGS at last of follow-up, observing significant differences between the groups (MWW, p=0.018) with higher levels of IGS in ANA+ patients (Figure 1F). <h3>Conclusion</h3> Our analysis showed 2 different patterns in the reduction of ANA titers over time in children with SLE, with 26% of them becoming ANA negative after 6 months from diagnosis and remaining persistently negative during follow-up. Our data have important implications, specifically for the recruitment of patients into clinical trials, where the latest classification criteria of SLE require ANA positivity as entry criterion. A seronegative state may represent a different subcategory of patients with SLE with specific pathogenetic pathways, possibly independently from autoantibodies. Therefore, further studies are needed to confirm our data. <h3>Reference</h3> [1] Pisetsky DS, <i>Nat Rev Rheumatol</i>. 2020. <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> None Declared.